The disclosed technology relates to a lubricant additive component for internal combustion engines, having no or low ash but high basicity.
The formulation of engine oils which contain reduced metal content (expressed as sulfated ash, ASTM D 874) but sufficient basicity (expressed as Total Base Number, TBN, ASTM D 2896) to adequately neutralize acidic combustion products while continuing to provide good protection to engine components has remained elusive. Low ash is desirable to minimize fouling of catalysts and other pollution control devices in the exhaust stream, which may be caused by migration of metal ions from the lubricant into the exhaust system. Metal containing detergents, however, and especially overbased metal-containing detergents, have long been a key to protecting engine parts from attack by acidic exhaust components that may enter the lubricant system by piston ring blow-by. It is desirable to attain these seemingly contradictory goals while still providing excellent lubrication and protection to the engine.
There have been many attempts to design overbased detergents. For example, U.S. Pat. No. 5,827,805, Adams et al., Oct. 27, 1998, discloses a salt represented by the structure
where Ar is an aromatic group, each R is independently a hydrocarbyl or substituted hydrocarbyl group, at least one R group having at least 8 carbon atoms, a is 1 to 4, R′ is hydrogen or alkyl, Mn+ is a quaternary ammonium ion or a metal ion of valence n, and q is a number up to n. The salts can be neutral salts, partially neutralized salts, or overbased salts. The overbased materials are prepared by reacting an acidic material with a mixture comprising the initial lactone or carboxylic acid product, a stoichiometric excess of a metal base, and a promoter. The compositions disclosed are useful as lubricant and fuel additives.
U.S. Patent Application Publication 2006/0247140, Cressey et al., Nov. 2, 2006, discloses a sulphur free reaction product of a hydrocarbyl substituted aromatic compound containing an acidic group and an organic nitrogen-containing base reacted with the acidic group. The organic nitrogen-containing base may be, among other materials, a tetraalkylammonium salt. It is said to be advantageous to use a strong organic nitrogen-containing base such as tetraalkylammonium hydroxide to neutralize an oligomeric reaction product prepared by reacting an alkylphenol such as dodecylphenol and an aldehyde such as formaldehyde. The compositions disclosed are said to be useful in a method for lubricating an internal combustion engine.
U.S. Pat. No. 3,962,104, Swietlik et al., Jun. 8, 1976, discloses lubricating oils containing as an ashless detergent a quaternary ammonium salt derived from an organic acid and a cation obtained by the reaction of a tertiary amine, olefin oxide and water. The quaternary ammonium hydroxides are disclosed as
Tertiary amines which are suitable include, among others, amines of the formula R1R2R3N such as, among others, trimethyl amine; or pyridine and substituted pyridines. The organic acids include, among others, carboxylic acids, phenols, sulphurized phenols, and sulphonic acids.
U.S. Pat. No. 5,688,751, Cleveland et al., Nov. 18, 1977, discloses salicylate salts as lubricant additives for two-cycle engines. The salt of the salicylic acid may be a basic metal salt, also known as an overbased salt. The hydroxyaromatic carboxylic compound can also be in the form of an ammonium salt or a hydrocarbylamine salt (i.e., a quaternary nitrogen salt). Appropriate amines can by hydrocarbyl primary, secondary, or tertiary amines.
PCT Publication WO 2008/075016, Jun. 26, 2008, discloses a nonaqueous lubricating oil composition comprising a major amount of abase oil and a minor amount of an additive which is a salt of general formula C+A−, with the cation, C+, being a quaternary phosphonium or quaternary ammonium ion having four hydrocarbyl groups. The anions may be of the general formula [R1R2P(O)O]− or sulfosuccinate esters or carboxylate anions.
PCT Publication WO 2006/135881, Dec. 21, 2006, discloses a quaternary ammonium salt detergent for use in fuels. The quaternary ammonium salt is the reaction product of (a) a hydrocarbyl-substituted acylating agent and a compound having an oxygen or nitrogen atom capable of condensing with said acylating agent and further having a tertiary amino group; and (b) a quaternizing agent suitable for converting the tertiary amino group to a quaternary nitrogen.
U.S. Pat. No. 5,531,911, Adams et al., Jul. 2, 1996, discloses functional fluids such as lubricants comprising the reaction product of an amine and a sulfonic acid as an anti-rust agent. The sulfonic acid may include mono-, di-, and tri-alkylated benzene and naphthalene sulfonic acids. The amines include primary, secondary, and tertiary amines. A particularly useful product is the ethylenediamine salt of dinonylnaphthalenesulfonic acid.
European Patent EP 0 727 477 B, Mar. 14, 2001, discloses ash-free detergents in lubricating oils. Calixarenes are used to complex a moiety derived from an organic nitrogen-containing base, typically a guanidine or ammonium, preferably a guanidine salt.
U.S. Pat. No. 3,362,801, Fareri et al., Jan. 9, 1968, discloses hydrocarbon oil composition containing alkyl quaternary ammonium salicylates. The hydrocarbon oil may be a fuel oil blend.
The disclosed technology, therefore, solves certain of the above-identified problems by employing a quaternary pnictogen detergent.